This parallel group dose-ranging study of MK-0677 in Growth Hormone (GH) Deficient children is part of a multicenter trial to study this oral drug in children with idiopathic GH deficiency. Subjects must be at least 4 years of age, prepubertal, and on GH therapy for at least one year prior to enrollment. Subjects who respond to a single test dose of Mk-0677 will be randomized to receive either one of four daily doses of MK-0677 or continued on GH injections. Growth velocity, IGF-1 and IGFBP-3 levels will be measured as mediators of efficacy. The potential benefit of avoiding daily injections of GH is an important reason for performing this study.